The transalveolar sinus elevation, often called closed or also osteotome technique is based on a technique developed by Summers and published in the early 90s. Summers used a set of sharp osteotomes of increasing diameter in order to create a controlled fracture of the sinus floor and consequently push bone debris from the sides of the osteotomy to an apical direction, creating the space necessary under the sinus membrane in order to place implants. Ever since the publication of Summers however, there has been so many modifications and changes introduced to the transalveolar technique that today it is difficult to identify a single standard. The basic principle however remains the same: the creation of a controlled fracture of the sinus floor and the creation of a space under the membrane with or without the use of grafting material. There is a wide variety of osteotomes available today, either as generic instruments or specific to certain systems and techniques. Nevertheless, some critical elements of osteotomes have to do with the type of the edge and the shape of the engaging part of the instrument. A concave edge is more aggressive and will concentrate more force on a smaller surface. It is indicated in cases of harder cortical bone, but will require precise control. When using this type of instrument after the preparation of the osteotomy, the force is gathered at the margins of the osteotomy and often pushes the fractured segment of the sinus floor to an apical direction. A convex edge of the osteotome is less aggressive and safer to use in cases of softer bone. Such an edge is more likely to create a less defined dome-like fracture of the sinus floor and it is usually safer than the concave edge. Furthermore, the engaging part of the osteotome can be either parallel or tapered. A tapered instrument will condense the bone laterally at the same time as advancing in an apical direction. This can be beneficial in cases of soft spongious bone. Now let's take a quick overview of how this could be applied in a typical patient case. Our patient is going to receive two implants in a segment of his posterior maxilla. After the three-dimensional radiographic assessment, we have calculated that the bone height to the sinus floor is 6 and 4 mm, respectively. Let's see the implant in the 6 mm site first. Here we are looking to generate two more millimetres from the sinus. To start with, we identify the place of the osteotomy and then, we continue preparing the osteotomy stopping short of 1 mm to the sinus. That is drilling for 5 mm. After the final drill, we place the osteotome. Gentle knocking with the mullet will be enough to create a small, controlled fracture of the sinus floor and give us two additional millimetres for implant placement. Let's now move to the 4 mm site. In this case, we need to elevate the sinus floor for another 4 mm. To achieve this without perforating the membrane, we often have to use some grafting material. Again, we mark the osteotomy and continue preparing to the last drill, stopping short of 1 mm from the sinus floor. After the final drill, we place again the osteotome and create a controlled fracture, adding another 1 to 2 mm to our preparation length. We would then use our grafting material to gently elevate the sinus floor for the last remaining 2 mm. Attention! At this stage, please remember the gentleman who just popped out! This is the famous Renaissance anatomist Antonio Valsalva and I'm sure you're all familiar with the Valsalva manoeuvre! Remember, the sinus membrane is like a balloon with only one narrow opening high at the ostium. If this opening gets blocked, and the sinus can no longer drain through the nose, chronic sinusitis and major problems can follow. Loose biomaterial in the sinus can quickly accumulate and block the ostium. It is crucial therefore to ensure that the membrane is intact before you place any biomaterials in the sinus. After a negative Valsalva sign, we can place grafting particles in the osteotomy and with gentle moves of the osteotome, gradually push them apically under the membrane creating the 4 mm required for the placement of our implant. The transalveolar sinus elevation technique is widely practised today and most research points to a high survival rate of the implants placed this way. Prevalence of membrane perforation is reported around 4%, while other complications include tinnitus and low prevalence of nausea, post operative infections of the surgical wound or the sinus. Nevertheless, it is a technique that allows no visual inspection and no margin for errors. Rare but dangerous complications have also been reported, such as the case of a patient with a severe bleeding which required hospitalisation. As with everything, careful patient selection and plan as well as good preparation and education of the operator is the key to success.
